Expansion joint for a fire-rated ceiling system

ABSTRACT

The cross member of a ceiling system is connected to the main runner of a ceiling system by a slide lock tab. A tab is bent at a 90* angle to the longitudinal axis of the cross runner. This tab slides into a fastener on the main runner structure. The connecting element between the cross member proper and the tab is corrugated so that, during a fire condition, the cross member can expand without buckling. Expansion occurs due to the collapse of the corrugated structure.

United States Patent 1 Nute, Jr.

1 51 Mar. 27, 1973 |5 EXPANSION JOINT FOR A FIRE- RATED CEILING SYSTEM[75] Inventor: Ernest B. Nute, Jr., Mountville, Pa.

[73] Assignee: Armstrong Cork Company, Lancaster, Pa.

22 Filed: May 7,1971

[21] Appl. No.: 141,243

[52] US. Cl ..287/189.36 A, 52/232, 52/664 [51] Int. Cl ..Fl6b 7/04Field ofSearch ..287/189.36 A,

[56] 2 References Cited UNITED STATES PATENTS 2,990,921 Wilde ..28-7/18936 A Manske ..287/20.92 W Meredith ..287/l89.36 A X PrimaryExaminerDavid J. Williamowsky Assistant ExaminerWayne L. SheddAttorney-Clifford B. Price [57] ABSTRACT The cross member of a ceilingsystem is connected to the main runner of a ceiling system by a slidelock tab. A tab is bent at a 90 angle to the longitudinal axis of thecross runner. This tab slides into a fastener on the main runnerstructure. The connecting element between the cross member proper andthe tab is corrugated so that, during a tire condition, the cross membercan expand without buckling. Expansion occurs due to the collapse of thecorrugated structure.

5 Claims, 2 Drawing Figures Patented March 27, 1973 INVENTOR ERNEST B.UTE,JR. BY 6 r ATTORNEY EXPANSION JOINT FOR A FIRE-RATED CEILING SYSTEMBACKGROUND OF THE INVENTION 1. Field of the Invention The invention isdirected to a ceiling suspension system and, more particularly, to ajoint structure to render the ceiling system capable of resistingbuckling during fire.

2. Description of the Prior Art A number of patents have issued onfire-retardant ceiling suspension systems. Normally, the thin metal,long extending parts of a ceiling suspension system will expand greatlywhen there is a fire in the area below the suspended ceiling. If a meansis not provided-to permit these long members to expand, they will buckleand drop the ceiling boards to the floor. This then exposes the areaabove the ceiling to destruction from the fire. Consequently, it isadvantageous for the suspension system to expand and not buckle andthereby hold the ceiling panels in position and thus retard thespreading of fire.

U. S. Pat. No. 3,159,252 is typical of an expansion system for a ceilingsuspension system. In FIG. 6 of that patent, there is shown a bucklingthat occurs in the suspension system during fire. This buckling is socontrolled that the ceiling boards are still held in place by thesuspension system. Many other patents exist in the art, and they providea number of different ways for allowing expansion of the runners ofaceiling system.

The idea of using a tab to fasten a cross member to a main runner memberof a ceiling system is old in the art. Normally, this tab would beplaced on the end of the straight rib section of the vertical web of thecross member. Consequently, any expansion of the cross member wouldresult in a spreading action being applied to two adjacent main runners.This would-then permit the ceiling board to drop out of position frombetween the main runners.

SUMMARY OF THE INVENTION The main runner of a ceiling suspension systemis provided with a fastening means to receive the tab on the end of across member. The tab on the cross member extends at 90 angle from thelongitudinal dimension of the cross member. This tab slides into thefastening member on the main runner, and this holds the cross memberrelative to the main runner member. The connecting element between thetab and the main body of the cross member is provided with a corrugatedconfiguration. Also, the horizontal flange member of the cross member isprovided with a small lip. Consequently, when heat causes expansion of across member, the cross member is able to expand by action of thecollapsing of the corrugated structure and a riding up of the horizontalflange of the cross member up over the horizontal flange of the mainrunner. Consequently, expansion of the cross member is permitted withoutbuckling or bending of the cross member in the direction of itslongitudinally extending axis.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a top view of the jointstructure herein; and FIG. II is an isometric view of the jointstructure of FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT A conventional ceiling system iscomposed of a plurality of long main runner members which usually extendparallel to each other about 4' apart. The main runners are generally 12feet long and are interconnected together to form a span which runs fromone side ofa room to the opposite side. Spanningthe 4 foot gap betweenthe main runners, every 2 feet there are placed short cross members. Inthe grid pattern of 2 X 4 feet, there are positioned ceiling boards. Themain runners areprovided with a plurality of different fire-expansionsystems. The invention herein is directed to a joint for connecting thecross member to the main runner to provide the cross member with thecapability of expanding during tire.

The main runner assembly 2 like most main runner assemblies is composedof a horizontal flange 4 and a vertical web 6. On the vertical web 6 ofthe main runner, there is positioned a fastening means 8 for holding thecross member in position relative to the main runner. The fasteningmeans is basically two little taBs 10 which are bent to face each otherand define a slide structure into which can be inserted a portion of thecross member. The cross member 1 1 also has a vertical flange 12 and avertical rib member 14. Normally, the cross member flange 12 would buttup against the side of the flange 4 of the main runner. Herein, theflange of the cross member is provided with a bent-up lip 16 whichslightly overlies the upper surface of the flange 4 of the main runner.When looking at the suspended ceiling system from the floor area of theroom, the two horizontal flanges tend to blend together to form aneatappearing joint. It is possible to eliminate the lip and just make thecross member flange higher than the main runner flange.

Normally, a tab element 18 which is bent out at a angle from thelongitudinally extending axis of the cross member 11 would slide intothe fastening means 8 of the main runner. Shoulders 19 position the tabadjacent one side of the fastening means 8. A small dimple 20 on thecross member tab coacts with a small dimple on the main runner rib 6 toprovide a positive friction lock to prevent the tab from readily slidingout from the fastening means 8. The structure 22 interconnects the tab18 and the rib portion 14 of the cross member. This element 22 is formedwith a corrugated structure as best shown in FIG. I.

When there is a fire in the room below the ceiling system, the heat fromthe fire will cause the cross member to expand in the direction 24 shownby the arrow in FIG. I. The expansion of the cross member iscompensatedfor by a collapsing of the corrugated structure 22 which nowpermits the expansion of the main portion of the cross member. The lip16 lets the horizontal flange of the cross member ride up over thehorizontal flange of the main runner member. Since the structure existsat both ends of the cross member, the 24 inches long cross member isprovided with the capability of expanding upwards to one-half inch,which is more than adequate in normal circumstances. Since the crossmember now expands without buckling or without pushing two parallel mainrunners apart, the ceiling boards are now held in place in thesuspension system during a fire.

What is claimed is:

l. A ceiling suspension system in the form of a grid comprisinguniformly spaced main runner members extending parallel to each other, aseries of cross members extending between the main runner'members todefine the grid pattern, the improvement comprising an expansion iointfor connecting together the cross member to the main runner member, thejoint comprising a fastening means on the vertical rib of the mainrunner and a tab on an extension from the vertical rib of the crossmember, the extension between the main body of the vertical rib of thecross member and the tab being corrugated with the folds of thecorrugations being transverse to the longitudinal axis of the web, saidtab being connected to the fastening means of the main runner to connectthe main runner and cross member together and the corrugated structurepermitting, through its collapsing, the expansion of the cross memberunder the application of heat.

2. The structure of claim 1 wherein the horizontal flange of the crossmember is provided with a lip which overlies the upper surface of thehorizontal flange of the main runner member so that the flange of thecross member will slide up over theflange of the main runner member whenthe crossmember expands due to the influence of heat.

3. The structure of claim 2 wherein the fastening means on the mainrunner member vertical rib is a dual

1. A ceiling suspension system in the form of a grid comprisinguniformly spaced main runner members extending parallel to each other, aseries of cross members extending between the main runner members todefine the grid pattern, the improvement comprising an expansion jointfor connecting together the cross member to the main runner member, thejoint comprising a fastening means on the vertical rib of the mainrunner and a tab on an extension from the vertical rib of the crossmember, the extension between the main body of the vertical rib of Thecross member and the tab being corrugated with the folds of thecorrugations being transverse to the longitudinal axis of the web, saidtab being connected to the fastening means of the main runner to connectthe main runner and cross member together and the corrugated structurepermitting, through its collapsing, the expansion of the cross memberunder the application of heat.
 2. The structure of claim 1 wherein thehorizontal flange of the cross member is provided with a lip whichoverlies the upper surface of the horizontal flange of the main runnermember so that the flange of the cross member will slide up over theflange of the main runner member when the cross member expands due tothe influence of heat.
 3. The structure of claim 2 wherein the fasteningmeans on the main runner member vertical rib is a dual tab structureforming a channel arrangement into which the tab structure of the crossmember may be slid and a detent structure on the tab and vertical rib ofthe main runner to frictionally hold the tab structure from sliding outof the fastening means of the main runner structure.
 4. The structure ofclaim 1 wherein the corrugated structure is an integral part of thevertical rib of the cross member.
 5. The structure of claim 1 whereinthe corrugated structure is provided with a plurality of alternatingridges and grooves.